Microsoft Corp. software designed for, of all things, cash registers and slot machines played a persuasive role in the European Union's landmark antitrust case labeling it an abusive monopolist. The European Commission is expected to fine Microsoft hundreds of millions of euros next week and order it to offer a version of its ubiquitous Windows operating system without Windows Media Player audio-visual software installed.

If Competition Commissioner Mario Monti succeeds in getting Microsoft to reconfigure future versions of an operating system that runs more than 95 percent of all PCs -- still considered a longshot by some industry observers -- a piece of Microsoft software known as Windows XP Embedded could be the reason. The commission says that by bundling Windows Media Player with its operating system, Microsoft is stifling competition in a market that is rapidly becoming a favorite method for consumers to listen to music and watch movies. Microsoft argues removal of Windows Media Player will limit, if not make impossible, the ability to play songs and film clips on a PC.